Goodwill and Intangible Assets (Goodwill) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Goodwill [Roll Forward]
Goodwill, Beginning Balance	[1]	$ 7,381	$ 7,395
Contribution	[2]		(14)
Acquisition	[3]	24
Goodwill, Ending Balance	[1]	7,405	7,381
Corporate and Other
Goodwill [Roll Forward]
Goodwill, Beginning Balance	[1]		14
Contribution	[2]		(14)
Operating Segments | Dominion Energy Virginia
Goodwill [Roll Forward]
Goodwill, Beginning Balance	[1]	2,106	2,106
Goodwill, Ending Balance	[1]	2,106	2,106
Operating Segments | Gas Distribution
Goodwill [Roll Forward]
Goodwill, Beginning Balance	[1]	3,512	3,512
Goodwill, Ending Balance	[1]	3,512	3,512
Operating Segments | Dominion Energy South Carolina
Goodwill [Roll Forward]
Goodwill, Beginning Balance	[1]	1,521	1,521
Goodwill, Ending Balance	[1]	1,521	1,521
Operating Segments | Contracted Assets
Goodwill [Roll Forward]
Goodwill, Beginning Balance	[1]	242	242
Acquisition	[3]	24
Goodwill, Ending Balance	[1]	$ 266	$ 242

[1] Goodwill amounts do not contain any accumulated impairment losses.

[2] See Note 9 for additional information including amounts reclassified to held for sale at December 31, 2020.

[3] See Note 3 for more information.